1. Field of the Invention
The present invention relates to a DNA aptamer specifically binding to pLDH (Plasmodium Lactate Dehydrogenase) and a composition for the diagnosis of malaria.
2. Description of the Related Art
Symptoms of malaria include headache, myalgia, fever, vomiting, and the like. However, malaria cannot be diagnosed on the basis of these symptoms because they are not unique to malaria. Typically, malaria is confirmed by microscopic examination, which is, however, unsuitable for use in initial diagnosis in malaria prevalent regions because the method requires expensive instruments and skilled operators. An immunochromatographic diagnosis assay provides a potential alternative. Based on antigen-antibody reactions, typical immunochromatographic portable diagnosis kits, however, may vary in diagnostical accuracy depending on the storage environment thereof. An initial countermeasure in response to an initial diagnosis performed in the scene of outbreak of malaria has a great influence on the subsequent treatment of malaria, so that portable diagnosis kits must have high performance.
pLDH is an essential enzyme, detectable in malarial parasites over their entire life, and one that is involved in the metabolism of malarial parasites. All four kinds of malarial parasites have the enzyme in a highly conserved amino acid sequences. Most of the currently available portable malaria diagnostic kits are based on antibodies to pLDH and can be used to diagnose all four types of malaria.
An aptamer is a single strand DNA (ssDNA) or RNA (ssRNA) that binds to a specific target. Thanks to their high affinity and stability to a specific target, they have recently been extensively developed and actively applied to the therapy and sensors for diagnosis of diseases. The synthesis of aptamers can be relatively simply, and cells, proteins and even small organic substance can be utilized as their targets, which allows for the development of new detection methods. In addition, aptamers find a wide range of applications in various fields, including the development of therapeutics, drug delivery systems, biosensors for diagnosis, etc. because they are superior in specificity and stability to the antibodies that were developed previously.
Antibodies developed for diagnostic use are prepared using the immune system and thus suffer from the disadvantage of their preparation consuming comparatively a lot of time and expense. Further, they are proteins that have poor stability, compared to aptamers, DNA or RNA, which may act as an obstruction to the development of highly sensible sensors. In light of the fact that most malaria-prevalent regions are hot and moist, diagnostic systems based on antibodies show low accuracy.
There is therefore a need for a diagnosis system of malaria that can overcome problems encountered in the prior art.